Closed
Description
Given the following code: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2021&gist=ef40cf437f8d092234c378e4c9b22d4e
struct Thing<X>(X);
trait Method<T> {
fn method(self) -> T;
}
impl<X> Method<i32> for Thing<X> {
fn method(self) -> i32 { 0 }
}
impl<X> Method<u32> for Thing<X> {
fn method(self) -> u32 { 0 }
}
fn main() {
let thing = Thing(true);
thing.method();
}The current output is:
error[E0283]: type annotations needed
--> src/main.rs:17:11
|
17 | thing.method();
| ------^^^^^^--
| | |
| | cannot infer type for type parameter `T` declared on the trait `Method`
| this method call resolves to `T`
|
note: multiple `impl`s satisfying `Thing<bool>: Method<_>` found
--> src/main.rs:7:1
|
7 | impl<X> Method<i32> for Thing<X> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
11 | impl<X> Method<u32> for Thing<X> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: use the fully qualified path for the potential candidates
|
17 | <Thing<X> as Method<i32>>::method(thing);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
17 | <Thing<X> as Method<u32>>::method(thing);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Neither of the suggestions compiles, because X does not refer to anything inside the body of main.
error[E0412]: cannot find type `X` in this scope
--> src/main.rs:17:12
|
17 | <Thing<X> as Method<i32>>::method(thing);
| ^ not found in this scope
|
help: consider importing this struct
|
1 | use nalgebra::coordinates::X;
|Instead, a correct suggestion would use any of the following 5 correct possibilities:
<Thing<bool> as Method<i32>>::method(thing);<Thing<_> as Method<i32>>::method(thing);<_ as Method<i32>>::method(thing);<Method<i32>>::method(thing);Method::<i32>::method(thing);